class Solution {
public:
    vector<string> readBinaryWatch(int num)
    {
        vector<string> v;
        for(int i = 0;i < 12;++i) {
            for(int j = 0;j < 60;++j) {
                if(__builtin_popcount(i) + __builtin_popcount(j) == num) {
                    v.push_back(to_string(i) + ":" + (j > 9 ? to_string(j) : "0" + to_string(j)));
                }
            }
        }
        return v;
    }
};